Transmitting device, receiving device, packet transfer system,packet transfer method, and packet transfer program

ABSTRACT

A transmission device (10) includes a flow table (11) that stores identification information about an uninterruptible target flow; a transmission-side identification unit (12) that identifies whether a received packet is from the target flow or a non-target flow based on whether the received packet matches the identification information about the target flow stored in the flow table (11); a tag application unit (13) that applies, to packets from the target flow, an uninterruptible identifier indicating that the packets are from the target flow and a sequence number for distinguishing the packets from other packets; and a branch unit (14) that branches the packets from the target flow processed by the tag application unit (13) into packets to be transferred to an active path (41) among redundant routes and packets to be transferred to a backup path (42) among the redundant routes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application under 35 U.S.C. § 371of International Application No. PCT/JP2019/024484, having anInternational Filing Date of Jun. 20, 2019, the disclosure of which isconsidered part of the disclosure of this application, and isincorporated in its entirety into this application.

TECHNICAL FIELD

The present invention relates to a transmission device, a receptiondevice, a packet transfer system, a packet transfer method, and a packettransfer program.

BACKGROUND ART

An uninterruptible switching control for packets in a network is atechnique for continuously establishing a communication by using abackup-system route without causing a packet loss (i.e.,uninterruptibly) even when a failure occurs in an active-system routeamong redundant routes (when a failure occurs in one of two systems).Accordingly, a plurality of routes which have the same combination of astart point and an end point but have different relay destinations areprepared in advance as redundant routes.

Patent Literature 1 describes, as an example of the uninterruptibleswitching control, a method for making a plurality of copies of packetstransmitted from a transmission device, transmitting the packets toredundant routes, buffering the plurality of packets received by areception device in a memory, selecting one of the same packets, andtransferring the selected packet.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Laid-Open No. 2005-102157

SUMMARY OF THE INVENTION Technical Problem

The uninterruptible switching control has been performed withoutexception on all flows of lines for the same route (same destination).Accordingly, a burden on the reception device increases as a flow rateincreases. For example, as the length of a redundant route increases, adelay difference between a first packet transmitted via an active-systemroute and a second packet transmitted via a backup-system routeincreases. Therefore, there is a need for a higher level of memoryperformance (memory capacity, memory processing speed) of a receptiondevice for buffering the first packet until the second packet isarrived.

FIG. 7 is a configuration diagram illustrating an uninterruptibletransfer system of related art. A transmission-side router 31 to beconnected to a transmission device 10 z accommodates two user networks(NW-A, NW-B). A reception-side router 32 to be connected to a receptiondevice 20 z also accommodates two user networks. In the figure, a flowof the user network (NW-A) is represented by “A” and a flow of the usernetwork (NW-B) is represented by “B”. Two redundant routes (an activepath 41 and a backup path 42) are formed from the transmission device 10z to the reception device 20 z. The active path 41 is a working paththat directly connects the transmission device 10 z and the receptiondevice 20 z. The backup path 42 is a protection path that connects fromthe transmission device 10 z to the reception device 20 z via a relaydevice 33.

In this case, in the two flows “A, B”, copies of all packets are madeand the same packets are caused to flow to each of the active path 41and the backup path 42 by an uninterruptible switching control.

However, the reception device 20 z needs to collectively performreception processing on all flows, so that a load is concentrated.Accordingly, there is a concern that deficiency in performance may occurdue to an increase in the number of users (users C, D, . . . ) in thefuture.

Accordingly, a major object of the present invention is to reduce aburden on the reception device in the uninterruptible switching control.

Means for Solving the Problem

To attain the above-described object, a transmission device according tothe present invention has the following features. The present inventionincludes a flow storage unit that stores identification informationabout an uninterruptible target flow; a transmission-side identificationunit that identifies whether a received packet is from the target flowor a non-target flow based on whether the received packet matches theidentification information about the target flow stored in the flowstorage unit;

a tag application unit that applies, to packets from the target flow, anuninterruptible identifier indicating that the packets are from thetarget flow, and a sequence number for distinguishing the packets fromother packets; and

a branch unit that branches the packets from the target flow processedby the tag application unit into packets to be transferred to an activepath among redundant routes and packets to be transferred to a backuppath among the redundant routes.

Effects of the Invention

According to the present invention, it is possible to reduce a burden ona reception device in uninterruptible switching control.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram illustrating a packet transfer systemaccording to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a computer used in the packettransfer system according to the present embodiment.

FIG. 3 is a detailed block diagram illustrating each device in thepacket transfer system according to the present embodiment.

FIG. 4 is an explanatory diagram when first flow identificationinformation according to the present embodiment is used.

FIG. 5 is an explanatory diagram when second flow identificationinformation according to the present embodiment is used.

FIG. 6 is a flowchart illustrating processing in a management serveraccording to the present embodiment.

FIG. 7 is a configuration diagram illustrating an uninterruptibletransfer system of related art.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention will be described in detail belowwith reference to the drawings.

FIG. 1 is a configuration diagram illustrating a packet transfer system.

A transmission-side router 31 that is connected to a transmission device10 accommodates two user networks (NW-A, NW-B). A reception-side router32 that is connected to a reception device 20 also accommodates two usernetworks. A flow of the user network (NW-A) is represented by “A”, and aflow of the user network (NW-B) is represented by “B”.Two redundant routes (an active path 41 and a backup path 42) are formedfrom the transmission device 10 to the reception device 20. The activepath 41 is a working path that directly connects the transmission device10 and the reception device 20. The backup path 42 is a protection paththat connects from the transmission device 10 to the reception device 20via the relay device 33.

Main differences between a system illustrated in FIG. 7 and a systemillustrated in FIG. 1 will be described below.

The transmission device 10 z illustrated in FIG. 7 transfers packetscopied for all flows “A, B” of the same destination without exception tothe backup path 42. On the other hand, the transmission device 10illustrated in FIG. 1 transfers only packets from the uninterruptibletarget flow “A” designated from a management server 60 to the backuppath 42, and excludes the uninterruptible non-target flow “B”, which isnot designated, from the uninterruptible switching control target.

The reception device 20 executes uninterruptible processing on thepackets from the target flow “A” (for details, see FIG. 3 ) andtransfers the packets to the reception-side router 32, while thereception device 20 does not execute the uninterruptible processing onthe non-target flow “B” and directly transfers the packets to thereception-side router 32.

The management server 60 sets, in the transmission device 10, the targetflow “A” on which the uninterruptible is executed in response to arequest from a user terminal 50. The user terminal 50 causes a user todefine the target flow “A” (for details, see FIGS. 4 and 5 ).

FIG. 2 is a block diagram illustrating a computer used in the packettransfer system.

Each of the devices in the packet transfer system, such as the userterminal 50, the management server 60, the transmission device 10, andthe reception device 20, which are described in FIG. 1 , is configuredas a computer 900 including a CPU 901, a RAM 902, a ROM 903, a HDD 904,a communication I/F 905, an input/output I/F 906, and a media I/F 907.The communication I/F 905 is connected to an external communicationdevice 915. The input/output I/F 906 is connected to an input/outputdevice 916. The media I/F 907 reads or writes data from or to therecording medium 917. Further, the CPU 901 controls each processing unitby executing a program (or an application, which can be abbreviated as“app”) loaded into the RAM 902. This program can be distributed via acommunication line, or can be recorded on the recording medium 917, suchas a CD-ROM, to be distributed.

FIG. 3 is a detailed block diagram of each of the devices in the packettransfer system.

The management server 60 includes a device setting unit 61 and adatabase 62. The device setting unit 61 reflects the setting for thetarget flow requested from the user terminal 50 in the transmissiondevice 10. In this case, the device setting unit 61 may determinewhether a new target flow can be received, and may reflect the settingfor the target flow if the new target flow can be received. Thus, it ispossible to prevent excess of the throughput of the network system inadvance. The database 62 stores various settings for the target flowwhen it is determined that the target flow can be received. Examples ofthe various settings for the target flow include network configurationdata, available buffer amount management data in the reception device20, and uninterruptible setting management data.

The transmission device 10 includes a flow table (flow storage unit) 11,a transmission-side identification unit 12, a tag application unit 13,and a branch unit 14.

In the flow table 11, target flow setting information is set accordingto an instruction from the device setting unit 61.

The transmission-side identification unit 12 identifies whether packetsreceived from an external device, such as the transmission-side router31, are from the target flow defined in the flow table 11. Packets fromthe target flow are transferred from the transmission-sideidentification unit 12 to the tag application unit 13, and packets froma non-target flow are transferred from the transmission-sideidentification unit 12 to the active path 41.The tag application unit 13 applies a sequence number and anuninterruptible identifier (for details, see FIGS. 4 and 5 ) immediatelyafter an ETH header of each packet from the target flow. Note that thesequence number is used to identify the same packets between a firstpacket received via the active path 41 and a second packet received viathe backup path 42. The uninterruptible identifier indicates that thepackets in the own device are from the target flow.The branch unit 14 branches (copies) the packets from the target flowinto two systems, and transfers the packets to each of the active path41 and the backup path 42.

The reception device 20 includes a reception-side identification unit21, an active system memory 22, a backup system memory 23, a readingunit 24, and a selection unit 25.

The reception-side identification unit 21 identifies the receivedpackets into the target flow and the non-target flow depending onwhether the uninterruptible identifier is present or not. The firstpacket from the target flow is stored in the active system memory 22,and the second packet from the target flow is stored in the backupsystem memory 23. The first packet from the non-target flow is directlycommunicated to the selection unit 25. The reading unit 24 refers to thesequence number, and absorbs a delay difference between the first packetread from the active system memory 22 and the second packet read fromthe backup system memory 23. In other words, one of the first packet andthe second packet to which the same sequence number is assigned iscommunicated to the selection unit 25.The selection unit 25 receives the packets from the target flow and thepackets from the non-target flow, and transfers the packets to theexternal device such as the reception-side router 32. In this case, itmay be desirable for the selection unit 25 to preferentially select thepackets from the target flow than the packets from the non-target flowand to transfer the packets to the external device. Thus,uninterruptible packets with a higher service request are processedpromptly, thereby making it possible to increase the user's satisfactionlevel.Note that the sequence number and the uninterruptible identifier in eachpacket are deleted before the packet is transferred to the externaldevice.

FIG. 4 is an explanatory diagram when first flow identificationinformation is used.

The flow table 11 stores, as a list of target flow identificationinformation, information 101 indicating a combination of a destinationIP address (IP-DA), a source IP address (IP-SA), and ToS (Type ofService).

The transmission-side identification unit 12 identifies a packet 102that matches the information 101, which indicates the combination of<IP-DA, IP-SA, ToS> and is stored in the flow table 11, as the targetflow.

The tag application unit 13 applies the sequence number (SN) and theuninterruptible identifier immediately after the ETH header of thepacket 102 from the target flow, and obtains a packet 103 to betransmitted.

The combination information 101 consists only of standard headerinformation, such as <IP-DA, IP-SA, ToS>, which is included in almostall packets. This facilitates the user to designate the target flow.Further, in a case where different IP-SAs are used for respectivedepartments in the same company, more detailed designation can beperformed, for example, when only the flow for a specific department ispreferentially set.

FIG. 5 is an explanatory diagram when second flow identificationinformation is used.

The flow table 11 stores, as a list of target flow identificationinformation, information 111 indicating a combination of VLAN-ID(Virtual Local Area Network-ID) and CoS (Class of Service).

The transmission-side identification unit 12 identifies a packet 112that matches the information 111, which indicates the combination of<VLAN-ID, CoS> and is stored in the flow table 11, as the target flow.

The tag application unit 13 applies the sequence number and theuninterruptible identifier immediately after the ETH header of thepacket 112 from the target flow, and obtains a packet 113 to betransmitted. The combination information 111 consists only of a smallamount of header information, such as <VLAN-ID, CoS>. Accordingly, theburden on the transmission-side identification unit 12 to read theheader information can be reduced. That is, the throughput for thepacket 113 from the target flow can be enhanced.

FIG. 6 is a flowchart illustrating processing of the management server60. In S11, the device setting unit 61 receives, from the user terminal50, an order for setting the uninterruptible. This order includes, forexample, the following information.

-   -   An ID of a start point device from the target flow in the user        networks (NW-A, NW-B), an ID of an end point device, or a line        ID in the user networks (NW-A, NW-B)    -   A date and time when the target flow is used (e.g., 2019/6/12        10:00 to 2019/6/13 12:00)    -   Flow identification information illustrated in FIGS. 4 and 5    -   Target flow use band (e.g., 20 Gbps)

In S12, the device setting unit 61 calculates two redundant routes(routes for the active path 41 and the backup path 42) based on theorder received in S11. In S13, the device setting unit 61 calculates adelay difference between the two redundant routes obtained in S12. Notethat, as a delay amount in each route, a setting value for the delayamount preliminarily set in a server may be used, or an actuallymeasured value obtained by performing a delay measurement using a delaymeasurement function may be used. The delay measurement function isimplemented as, for example, OAM (Operations, Administration,Maintenance) functions of Ethernet(R). In S14, the device setting unit61 calculates a buffer amount required for buffering the target flow inthe reception device 20 based on the delay difference obtained in S13and the use band of the target flow. This calculation formula is, forexample, delay difference [2 ms]×use band [20 Gbps]=buffer amount 5[MBytes]. This makes it possible to continuously hold the first packet,which is first arrived, without being discarded from the receptiondevice 20, until the second packet, which is arrived next, reaches thereception device 20.

In S15, the device setting unit 61 determines whether an availablebuffer amount of the reception device 20 (active system memory 22)managed by the database 62 is greater than the required buffer amountcalculated in S14. If the determination result indicates Yes in S15, theprocessing proceeds to S16, and if the determination result indicatesNo, the processing proceeds to S18.

In S16, the device setting unit 61 adds identification information aboutthe current target flow to the flow table 11 through thetransmission-side identification unit 12. Then, the content of thedatabase 62 is updated based on the content of the added target flow. Asa result, for example, the available buffer amount of the active systemmemory 22 is subtracted by the amount corresponding to the requiredbuffer amount calculated in S14.In S17, the device setting unit 61 communicates information indicatingthat the order received in S11 is acceptable (OK) to the user terminal50.

-   -   In S18, the device setting unit 61 communicates information        indicating that the order received in S11 is refused (NG) to the        user terminal 50.

Advantageous Effects

The transmission device 10 according to the present invention includesthe flow table 11 that stores identification information about anuninterruptible target flow; the transmission-side identification unit12 that identifies whether a received packet is from the target flow ora non-target flow based on whether the received packet matches theidentification information about the target flow stored in the flowtable 11; the tag application unit 13 that applies, to packets from thetarget flow, an uninterruptible identifier indicating that the packetsare from the target flow, and a sequence number for distinguishing thepackets from other packets; and the branch unit 14 that branches thepackets from the target flow processed by the tag application unit 13into packets to be transferred to the active path 41 among redundantroutes and packets to be transferred to the backup path 42 among theredundant routes.

With this configuration, the number of packets to be transmitted fromthe transmission device 10 to the redundant route is reduced, therebymaking it possible to reduce a burden (request performance such as abuffer memory amount) on the reception device 20. In practice, it isless likely to receive an order for setting all flows as theuninterruptible target flow, and in many cases, only some importantflows are set as the target flow, thereby making it possible to satisfythe user's needs.

The reception device 20 according to the present invention includes thereception-side identification unit 21 that identifies whether a receivedpacket is from an uninterruptible target flow or a non-target flow; amemory (active system memory 22, backup system memory 23) that storespackets from the target flow identified by the reception-sideidentification unit 21; the reading unit 24 that reads one packet from aplurality of the same packets from the target flow, the plurality of thesame packets being present in the memory; and the selection unit 25 thatselects and sequentially transfers the packets from the target flow readby the reading unit 24 and packets from the non-target flow identifiedby the reception-side identification unit 21.

Consequently, it is possible to reduce a burden (request performancesuch as a buffer memory amount) on the reception device 20 by limitingthe uninterruptible switching control in the reception device 20 only tothe packets from the target flow.

The packet transfer system according to the present invention includesthe transmission device 10 and the management server 60 that setsidentification information about the target flow stored in the flowtable 11. The management server 60 calculates a memory amount requiredfor buffering the target flow based on the delay difference between theactive path 41 and the backup path 42 with respect to the receptiondevice 20 that receives packets from the target flow, and permitssetting of the identification information about the target flow in theflow table 11 when the reception device 20 can provide a memory amountmore than the required memory amount.

With this configuration, the identification information about the targetflow depending on the performance of the reception device 20 can be setin the flow table 11, thereby preventing deficiency in performance ofthe reception device 20 before the flow is allowed to pass.

REFERENCE SIGNS LIST

-   -   10 Transmission device    -   11 Flow table (flow storage unit)    -   12 Transmission-side identification unit    -   13 Tag application unit    -   14 Branch unit    -   20 Reception device    -   21 Reception-side identification unit    -   22 Active system memory    -   23 Backup system memory    -   24 Reading unit    -   25 Selection unit    -   31 Transmission-side router    -   32 Reception-side router    -   33 Relay device    -   41 Active path    -   42 Backup path    -   50 User terminal    -   60 Management server    -   61 Device setting unit    -   62 Database

The invention claimed is:
 1. A transmission device comprising: a flowstorage unit that stores identification information about target flowthat is uninterruptible; a transmission-side identification unit thatidentifies whether a received packet is from the target flow or anon-target flow based on determining whether a combination of adestination address, a source address, and a type of service of thereceived packet or a combination of a virtual local areanetwork-identifier and a class of service of the received packet matchesa record included in the identification information about the targetflow stored in the flow storage unit; a tag application unit thatapplies, to packets from the target flow, an uninterruptible identifierindicating that the packets are from the target flow and a sequencenumber for distinguishing the packets from other packets; and a branchunit that branches the packets from the target flow processed by the tagapplication unit into i) packets to be transferred to an active path,that directly connects the transmission device and a reception device,and ii) packets to be transferred to a backup path, that connects thetransmission device to the reception device via a relay device.
 2. Areception device comprising: a reception-side identification unit thatreceives a first set of packets included in a target flow and a secondset of packets included in a non-target flow and identifies whether areceived packet is from the target flow or the non-target flow, thetarget flow being uninterruptible; a memory that stores the first set ofpackets from the target flow identified by the reception-sideidentification unit; a reading unit that reads, for each of the firstset of packets, one packet from a plurality of same packets from thetarget flow, the plurality of same packets being present in the memory;and a selection unit that receives the first set of packets included inthe target flow and the second set of packets included in the non-targetflow, selects the first set of packets in the target flow read by thereading unit and transfers the first set of packets in the target flowto an external device, and after transferring the first set of packetsin the target flow, transfer the second set of packets from thenon-target flow identified by the reception-side identification unit tothe external device.
 3. A packet transfer system comprising: atransmission device according to claim 1; and a management server thatsets identification information about the target flow stored in the flowstorage unit, wherein the management server calculates a memory amountrequired for buffering the target flow based on a delay differencebetween the active path and the backup path with respect to a receptiondevice that receives packets from the target flow, and permits settingof the identification information about the target flow in the flowstorage unit when the reception device can provide a memory amount morethan the memory amount required for buffering the target flow.
 4. Apacket transfer method comprising: storing identification informationabout a target flow in a flow storage unit, the target flow beinguninterruptible; identifying whether a received packet is from thetarget flow or a non-target flow based on determining whether acombination of a destination address, a source address, and a type ofservice of the received packet or a combination of a virtual local areanetwork-identifier and a class of service of the received packet matchesa record included in the identification information about the targetflow stored in the flow storage unit; applying, to packets from thetarget flow, an uninterruptible identifier indicating that the packetsare from the target flow and a sequence number for distinguishing thepackets from other packets; and branching the packets from the targetflow into i) packets to be transferred to an active path, that directlyconnects a transmission device and a reception device, and ii) packetsto be transferred to a backup path, that connects the transmissiondevice to the reception device via a relay device.